card games: what's the crucial card in the game of hearts?

Questions

How many continents must a sport be played on before the IOC will consider making it an Olympic event for men?

How many karats is pure, unalloyed gold?

What singer songwriter had five albums in the Billboard Top 200 in 1977?

What amphibians do you raise if you run a ranarium?

What blonde was the subject of the four most expensive Andy Warhol works sold at auction?